Typical methods for manipulating computer generated and displayed images include the use of a mouse to select a scroll bar, or "Page Up" and "Page Down" keys. However, these methods are not intuitive and are not particularly well adapted for browsing or skim reading through a multi-page document, or for quickly searching through such a document to find a particular passage. There have been proposals for gestural control of computers or other electrical/electronic instruments, but these have been very abstract in terms of the lack of intuitive support for the control function to be imparted and have required a reasonably high degree of skill or training. A significant problem encountered in gestural control systems is the ambiguity of gestures, and their potential misinterpretation, particularly when several different users are involved.
The word "gesture" and similar in this specification, is used broadly to cover gestures such as pointing, touching, stroking, waving etc.